全文获取类型
收费全文 | 30002篇 |
免费 | 4412篇 |
国内免费 | 1193篇 |
专业分类
电工技术 | 847篇 |
综合类 | 1958篇 |
化学工业 | 1891篇 |
金属工艺 | 12393篇 |
机械仪表 | 5330篇 |
建筑科学 | 1805篇 |
矿业工程 | 909篇 |
能源动力 | 479篇 |
轻工业 | 602篇 |
水利工程 | 325篇 |
石油天然气 | 1807篇 |
武器工业 | 288篇 |
无线电 | 814篇 |
一般工业技术 | 3862篇 |
冶金工业 | 1473篇 |
原子能技术 | 151篇 |
自动化技术 | 673篇 |
出版年
2024年 | 172篇 |
2023年 | 461篇 |
2022年 | 673篇 |
2021年 | 737篇 |
2020年 | 863篇 |
2019年 | 883篇 |
2018年 | 942篇 |
2017年 | 1312篇 |
2016年 | 1316篇 |
2015年 | 1180篇 |
2014年 | 1785篇 |
2013年 | 2144篇 |
2012年 | 1987篇 |
2011年 | 2076篇 |
2010年 | 1583篇 |
2009年 | 1595篇 |
2008年 | 1292篇 |
2007年 | 2010篇 |
2006年 | 2028篇 |
2005年 | 1614篇 |
2004年 | 1590篇 |
2003年 | 1253篇 |
2002年 | 1006篇 |
2001年 | 928篇 |
2000年 | 836篇 |
1999年 | 630篇 |
1998年 | 525篇 |
1997年 | 467篇 |
1996年 | 400篇 |
1995年 | 332篇 |
1994年 | 224篇 |
1993年 | 149篇 |
1992年 | 151篇 |
1991年 | 114篇 |
1990年 | 89篇 |
1989年 | 87篇 |
1988年 | 62篇 |
1987年 | 34篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1959年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
钛容器的特点 总被引:2,自引:1,他引:1
黄嘉琥 《石油化工设备技术》1996,17(5):19-24
根据钛材的化学、物理、力学和工艺性能介绍了钛容器在设计、制造、检验和应用方面的特点。 相似文献
2.
G. Biallas Dr.‐Ing. C. Sick J. Schneider K.‐H. Trautmann 《Materialwissenschaft und Werkstofftechnik》2007,38(9):705-711
Biaxial fatigue of friction stir welded stiffened panels Within the framework of the European WelAir project, cruciform specimens made from stiffening FSW overlap joints were fatigued in the DLR biaxial test rig. To resemble the loading situation of pressurized fuselage structures, proportional loading without any phase shift, but with different load ratios λ between the loading components in both directions was applied.Natural crack initiation and subsequent crack growth were governed by the stiffness gradient caused by introducing the stringer. Cracks initiated and propagated at run‐in and run‐out locations in a direction perpendicular to the weld seam. The shortest fatigue life was observed for uniaxial loading in welding direction (λ = 0). An additional stress component perpendicular to the joint line (λ > 0) resulted in a higher number of cycles to failure. Similar to single stringer panels, increasing the load ratio also increased the number of cycles to failure for FSW clip‐stringer structural members, but additionally gives a different location of the fatal crack. 相似文献
3.
本文通过焊接试验对奥氏体不锈钢绕带容器环板与绕带焊接工艺进行了研究分析,并得出了合理的焊接方法和工艺参数。 相似文献
4.
We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance
of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading
conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases
as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of
fatigue processes on the surfaces. The comparative characteristics of coatings are presented.
__________
Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007. 相似文献
5.
Unconrolled agglomeration of particles and adhesion of the particulate mass to wall surfaces are common severe problems in many drying operations. This paper reviews the mechanisms of interparticle and particle-surface attraction as well as the theory and the existing tests for characterising powders in terms of internal strength, wall friction and adhesion. The usefulness of the information obtained from these tests in dryer design and operation is critically reviewed. The importance of powder stickiness in various types of dryers is discussed and established methods of combating the problem are presented Recommendations an made for further research in the area of powder cohesion and adhesion. 相似文献
6.
M. M. I. HAMMOUDA I. G. EL-BATANONY H. E. M. SALLAM 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(7):627-639
An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area. 相似文献
7.
设计一条钢筋网自动化焊接生产线,包括经料送料平台、纬料自动分料及上料机构、多点电阻点焊机、接料平台、卸料机械手。从上料到出料依靠电机、汽缸之间的协调工作来实现。并由单片机和PLC实现控制功能,上位机用MCGS组态软件在整个过程监视现场,采集工作状态及参数,起到监控作用。 相似文献
8.
Chih-Chun Hsieh Tao-Chih Chang Dong-Yih Lin Ming-Che Chen Weite Wu 《Metals and Materials International》2007,13(5):411-416
The purpose of this study is to investigate the precipitation characteristics of σ phase in the fusion zone of stainless steel
welds at various welding passes during a tungsten are welding (GTAW) process. The morphology, quantity, and chemical composition
of the δ-ferrite and σ phase were analyzed using optical microscopy (OM), a ferritscope (FS), a X-ray diffractometer (XRD),
scanning electron microscopy (SEM), an electron probe micro-analyzer (EPMA), and a wavelength dispersive spectrometer (WDS),
respectively. Massive δ-ferrite was observed in the fusion zone of the first pass welds during welding of dissimilar stainless
steels. The σ phase precipitated at the inner δ-ferrite particles and decreased δ-ferrite content during the third pass welding.
The σ and δ phases can be stabilized by Si element, which promoted the phase transformation of σ→ϱ+λ2 in the fusion zone of the third pass welds. It was found that the σ phase was a Fe−Cr−Si intermetallic compound found in
the fusion zone of the third pass welds during multi-pass welding. 相似文献
9.
NIU Jitai GUO Wei ZHANG Xinmei and LIU Xingqiu) State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin China) State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong University Shanghai China 《稀有金属(英文版)》2003,22(4)
Through the vacuum diffusion welding SiCp/ZL101 aluminum with Cu interlayer,the effect of welding parame-ter and the thickness of Cu on the welded joint property was investigated,and the optimal welding parameters were putforward at the same time.The microstructure of joint was analyzed by means of optical-microscope,scanning electron mi-croscope in order to study the relationship between the macro-properties of joint and the microstructure.The results showthat diffusion welding with Cu interlayer could be used for welding aluminum matrix composites SiCp/ZL101 successfully. 相似文献
10.
介绍2种单片机焊接控制器的功能参数及设计思路。一种采用80C196KB PSD311的16位总线结构;另一种采用89C52的8位总线结构。实践证明单片机系统是焊接设备中比较理想的控制器件。 相似文献